WASHINGTON -- Comet ISON is teasing the solar system as it dances with the sun and it's giving astronomers mixed signals. Will it meet a fiery death - or survive - when it whips around the sun on Thursday? The icy comet will be only about 1 million miles away from the sun's super-hot surface during its close encounter on Thanksgiving. On Monday, it looked like it was about to die even before it got there. On Tuesday, it appeared...

CAPE CANAVERAL, Fla. -- NASA hopes its newest Mars spacecraft lives up to its know-it-all name. The robotic explorer called Maven is due to blast off Monday on a 10-month journey to the red planet. There, it will orbit Mars and study the atmosphere to try to understand how the planet morphed from warm and wet to cold and dry. "A maven is a trusted expert," noted NASA's space science chief, John Grunsfeld. Maven will help scientists "build a story...

NASA scientists found faint signatures of water in the atmospheres of five distant planets. All five planets appear to be hazy. (NASA Goddard Space Flight Center) NASA's Hubble Space Telescope has detected water in the atmospheres of five planets beyond our solar system, two recent studies reveal. The are all scorching-hot, Jupiter-size worlds that are unlikely to host life as we know it. But finding water in their atmospheres still marks a step forward in the search for distant planets...